Stability of the Apoproteins of light-Harvesting-- Complex I and II during Biogenesis of Thylakoids in the Chlorophyll 6-less Barley Mutant Chlorina f2’

Transcription and translation of Lhc (cab) genes have been com-pared in the chlorina f2 mutant of barley (Hordeum vulgare) and its wild type to study the effect of chlorophyll b’s absence on the regulation of assembly of the light-harvesting complexes (LHC). All tested genes were transcribed and the amount of their respective mRNAs increased rhythmically upon illumination of etiolated mu-tant plants. l h e synthesis of individual LHC apoproteins also had a rhythmic pattern when total leaf protein extracts were examined, whereas they increased gradually in the thylakoid. Only some LHC pigment-proteins present in wild-type thylakoids were found in mature mutant membranes. Thus, only the 25-kD (type 3) apopro-tein of the three apoproteins of the major LHC Ilb complex sur-vived. The amount of the minor LHC II pigment-proteins was con-siderably reduced but not to zero. Photosystem I had some of the two LHC Ia apoproteins but had little of those of LHC Ib. This wa